The disclosed subject matter relates generally to vapor deposition and more particularly to cathodic arc vapor deposition.
Cathodic arc vapor deposition typically involves placing one or more workpieces in an evacuated deposition chamber or vessel along with one or more blocks of coating material. An electrical arc is initiated, for example by a trigger, which first contacts the coating material serving as a cathode. As the trigger is moved away from the cathode, the arc jumps between the coating material and an anode, which may be for example, an inside surface of the vessel. The arc vaporizes the cathodic coating material into a plasma, which contains positively charged ions that are attracted toward workpieces to be coated.
Cathodic arc coaters can use water or an aqueous solution to directly or indirectly cool the cathode. With indirect cathode cooling, coolant is provided to directly cool a stinger used to the steer the arc. Cooling the stinger indirectly cools the cathode primarily by conduction. However, high cathode temperatures can cause thermal stress cracking of the cathode due to limitations of the coolant. Higher boiling-point coolants such as glycol can reduce the thermal gradient but increase the risk that the magnets are heated above their Curie temperature, causing loss of magnetic arc steering control.